var welcome = 'hello';
welcome(); // 此⾏报错：TypeError: welcome is not a function
var str = Date.now() % 2 ? '奇数' : '偶数';
if (str !== '奇数') {
    alert('hello');
}
else if (str === '偶数') {
    alert('world');
}
var obj = { width: 10, height: 15 };
var area = obj.width * obj.heigh;
var message = "hello, world";
message.toUperCase();
